A Framework to Evaluate Omnidirectional Video Coding Schemes

Omnidirectional videos of real world environments viewed on head-mounted displays with real-time head motion tracking can offer immersive visual experiences. For live streaming applications, compression is critical to reduce the bitrate. Omnidirectional videos, which are spherical in nature, are mapped onto one or more planes before encoding to interface with modern video coding standards. In this paper, we consider the problem of evaluating the coding efficiency in the context of viewing with a head-mounted display. We extract viewport based head motion trajectories, and compare the original and coded videos on the viewport. With this approach, we compare different sphere-to-plane mappings. We show that the average viewport quality can be approximated by a weighted spherical PSNR.